Okay I've search and read the FAQ already.
But nothing came up that was clear and definative that would answer my questions about injector sizing.

I know how to size injectors : to : horsepower with regular fuel

? but what is the formula or scale to use for sizing injectors : to : horsepower using E85?



I'm sure this would help out all of the up and coming E85 users.
Charlie Moua

 

there isn't one that i'm aware of. I was told to get 800cc injectors for my 350whp goals but ended getting 1000cc and maxxed them out at only 377whp @ 9psi. GL

 

I use a dartboard and blindfold...

Actually, an easy way to figure the safe max for injectors is 0.6 x CC = whp. This is for four injectors on a Honda, typically nearing 85% duty cycle and a decent turbo setup. So 0.6 x 600cc = 360whp. You'll usually want to go 25-50% higher for more power later.

For E85, you the formula 0.45 x CC = whp works well. You need about 30% more fuel when using E85 vs 93 octane, but make 5-10% more max power. Just remember that counts for idle too, so the max injector size your EMS can control/idle with gasoline can be 30% larger.

 

Wow, 1000cc injectors maxed out at 375whp....
what's your MPG like during regular driving?

 

must be hella rich lol.

hp is the main thing that limits injector sizing. 880's on e85 ive seen go to 440-480 wheel. but this is with stock/close to stock base fuel pressure. you can always ramp up the base with a fpr and the injectors will flow more.

 

I got 680cc PTE injectors and walbro. How much they support hp with E85.

 

um, correct me if i'm wrong, but does anyone else see something wrong with these numbers?? 1000cc injectors maxed out at 377hp? i think u may possibly be running a lil rich

 

yea something doesnt seem right there. im only at 57% duty on my id1000's and im right at about 350 wheel at 11 lbs on a b16.

 

If you use this HP calculator and a BSFC of .750, it will give you a pretty good average for E85.

http://www.injectordynamics.com/hors...alculator.html

 

I was surprised too when my tuner told me the injectors were @ 100% cycle duty at 9lbs of boost. He couldn't tune any higher because of it and was actually running off the wastegate spring. Not sure what MPG is, I've driven the car twice since I got it tuned.
I was skeptical about the numbers but I watched as the laptop read 100% while on the dyno. My tuner recommends upgrading to a 1:1 fpr and/or upgrading the fuel lines before he would be able to turn up the boost on the mbc. I looked at the plugs just now and verified the the car is running a little on the rich side.
I still don't understand how my fuel system is inadequate...any thoughts on my setup?
-walbro 255
-precision 1000cc
-b&m fpr
-aem fuel rail
-blox fpg (reads 70 psi)
-everything else stock

 

something doesnt seem right. walbro 255 with a 70 base fuel? didnt think they could really support that.

on top of that add 9 psi of boost. making it almost 80 lbs of fuel pressure... :/

 

They can't I believe the internal relief lifts at 72lbs or so unless it's modded.